Mobile communications have taken up and provided the possibility of communication almost anywhere, as long access coverage is available. With the arrival of the 2.nd Generation (2G), 3G and 4G telecommunications networks, a wide variety of communication services have been developed.
A public mobile telecommunication operator provides services to its subscribers with legacy services as speech and data, and as well with services like e.g. Virtual Private Network (VPN) solutions, call diversion, ring-back services, and perceives a relation with a customer as an important asset.
Additionally to public mobile telecommunication services, as mentioned above, Wireless Local Area Networks (WLANs) have evolved, e.g. WLANs complying with the IEEE 802.11 suite, also denoted as WiFi. A WLAN offers also mobile telecommunication services, provided by applications such as Skype or FaceTime from Apple, mainly deployed by mobile User Equipment (UE) which are not designed to be used in public telecommunication networks, such as tablets or Laptop computers.
One of the capabilities, public mobile telecommunication operators offer to a subscriber, is to use a mobile UE (with a Subscriber Identity Module (SIM)) having WLAN capabilities, for a call setup wherein the mobile UE is located in a WLAN's coverage and operating via the WLAN. When setting up a call, the call setup is routed via the WLAN, via a server of an Internet Service Provider (ISP) in the Internet, towards the operator's domain for terminating the call setup. This capability increases the (in-door) coverage of a public mobile telecommunication network.
Tablets are generally not equipped with a Subscriber Identity Module (SIM) like mobile UE such as mobile phones or smartphones need to have for operating in a public mobile telecommunication network. The SIM is associated, by means of a database under control of the operator, with the subscriber's phone number and invoice address in case of post payment, and constitutes a binding between an operator and its client, the subscriber. The database under control of the operator is known as a Home Location Register (HLR) or Home Subscriber Server (HSS).
The use of a mobile UE with a SIM, such as a smartphone, and the use a mobile UE without a SIM, such as a tablet is different, as e.g. for a call setup where a geographical location of the calling mobile UE is required. A mobile UE with a SIM has the latest Location Update (LU) available in the HSS or HLR, while there is no actual position provided during a call setup by a mobile UE without a SIM, like a tablet.
When a mobile UE with a SIM operates in the public mobile telecommunication network, the latest LU, stored in a Home Subscriber Server, provides a geographical location of the mobile UE. However when the mobile UE with SIM has roamed into an area covered by a WLAN, and operates in that WLAN, the latest LU might not be the most accurate geographical location. In particular when an emergency centre is called, and the geographical location is provided by the HSS or HLR, the accuracy of the geographical location might not be as desired. An emergency centre is also known as Public Safety Answering Point (PSAP).
When a mobile UE without a SIM in a WLAN, such as a tablet calls an emergency centre, the emergency call is forwarded via the WLAN towards the operator's domain, and the actual geographical location information of the device or other useful information is not provided to the emergency centre.
Furthermore when subscribers of a mobile operator are using mobile UEs without a SIM, less possibilities for maintaining a relationship are present as the SIM, comprising an International Mobile Subscriber Identity (IMSI) having a unique identity in a range belonging to a particular operator, is absent. The SIM constitutes, apart from having an address to charge network usage, a binding with an operator's customer, enabling e.g. to make special offers.
Although the operator might have a geographical address, with State/Postal Code/City/Street/Number, of the associated mobile UE with SIM, which is applied for charging calls, this address does not necessarily be the address where the tablet resides during setting up an emergency call.
In some countries there is an obligation for public telecommunication operators according to national regulations, to provide geographical location information for calls setup to an emergency centre.
Additionally, the operator, in servicing and maintaining its subscribers, has no means to check whether a tablet without SIM that is making a call via the WLAN, is in a particular way associated with the subscriber's mobile UE with SIM.
Hence, there is a need for an enhanced call setup when a calling mobile UE operates in the WLAN environment.